JP2002063895A - Method of chemical conversion of batter case for lead acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of chemical conversion of high efficiency which does not require water tank equipment and overflow preventing tools nor adjustment of liquid volume or the specific weight, on the way of conversion or re- immersion, after conversion or the like. SOLUTION: In chemical conversion of a non-converted polar plate in a battery case, the process of repeating charging and discharging is to be involved during the conversion, before and after which process, charge current is to be changed for two steps or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a battery case of a lead storage battery.

[0002]

2. Description of the Related Art In a conventional method for forming a battery case of a lead storage battery, as shown in FIG. 3, for example, it is general that a constant current is applied to about 250% to 350% of the theoretical quantity of electricity of a positive electrode. At this time, the temperature of the battery rises due to overcharging, which adversely affects the formation and causes the battery case to swell. In order to prevent this, a method of supplying electricity in a water bath is generally used. In addition, in the case of a liquid type lead-acid battery in which a large amount of fluid is present even after chemical formation, for the purpose of improving the formation efficiency, after performing formation using dilute sulfuric acid having a constant specific gravity, the liquid is exchanged with a dilute sulfuric acid having a predetermined specific gravity. There was a way to do that.

[0003] Further, in a battery which is difficult to change the liquid, such as a control valve type lead storage battery in which the fluid after the formation is restricted, all necessary dilute sulfuric acid is injected before the start of the formation in order to prevent overflow. There was also a method in which the solution was injected again during the formation or after the formation was completed in order to adjust the amount or specific gravity of the solution.

Further, in the case of a method in which the liquid amount or specific gravity is not adjusted during the formation or after the formation is completed, and in the case of a battery having a narrow space in the battery case, in order to prevent overflow due to overcharging, a treatment for preventing overflow is performed. In some cases, tools were used.

[0005] Further, as disclosed in Japanese Patent No. 3018406, a method is used in which the battery voltage is increased and discharged before reversal, which is constant with respect to the formation time, then recharged and repolarized, and the current is reduced. There is also.

[0006]

In the conventional method of applying a current of about 250% to 350% of the theoretical quantity of electricity of the positive electrode at a constant current, a jig and a water tank for preventing overflow are required.
Further, in this method, the formation efficiency of the positive electrode is low, and P
The bO ₂ content was less than 90%.

Further, a method of replacing dilute sulfuric acid after chemical formation,
In the method of injecting dilute sulfuric acid during the chemical formation or after the completion of the chemical formation, an extra cost is required because the number of steps is increased. Furthermore, even by the method described in Japanese Patent No. 3018406, the formation efficiency was not sufficient, and the cost was still insufficient.

The present invention solves the above-mentioned problems of the prior art, does not require a water tank facility or an overflow preventing jig, and replaces dilute sulfuric acid after chemical formation, or during or after chemical formation. It is another object of the present invention to provide a low-cost method for forming a battery case of a lead storage battery having a high formation efficiency without necessity of adjusting a liquid amount or specific gravity of a liquid injection or the like.

[0009]

Means for Solving the Problems The first invention of the present application is a chemical conversion method for forming an unformed electrode plate in a battery case, and includes a step of repeating discharge and charge during the formation. This is a method for forming a battery case of a lead storage battery, wherein a charging current changes at least two stages before and after.

When the current at the start of formation is increased, the formation is completed in a short time, but the smaller the current, the higher the final formation efficiency. If the temperature of the battery becomes too high due to overcharging, the formation may be adversely affected and the battery case may swell. In addition, in a battery having a narrow space in the battery case, overflow is likely to occur. Therefore, by performing the discharge before that, the battery temperature decreases. Thereafter, when the battery is charged, the battery temperature rises again, so that the battery is discharged again. By repeating this several times,
Since the formation efficiency is improved and the amount of overcharge can be reduced, the battery case is less likely to swell or overflow.

After the repetition process of discharging and charging is completed,
Further, the battery is charged with a constant current. At this time, the liquid overflows most easily, so it is necessary to pay attention to the charging current. However, if the charging current is too small, the entire formation time is prolonged. Therefore, it is better that the charging current is large unless overflow occurs. As charging proceeds, the amount of liquid decreases due to gas generation, and overflow does not easily occur, so that charging current can be increased. However, if the current is too high here, the battery becomes too hot and the battery case swells, so there is no need to increase the current if there is a margin in the formation time.

The current at the start of the formation, the current after the end of the repetition of the steps of discharging and charging, and the current at the end of the formation eliminate the time restrictions such as the timing of the repetition of the steps of discharging and charging. As a result, the same value can be obtained as a result, but actually different values due to the existence of time constraints.

According to a second aspect of the present invention, in the method according to the first aspect, before the amount of electricity to be charged exceeds 100% of the theoretical amount of electricity of the positive electrode, the discharge in the process of repeating the discharge and the charge during the formation is started. It is characterized by doing so.

If the amount of electricity charged exceeds 100% of the theoretical amount of electricity of the positive electrode, the generation of gas sharply increases, and the overflow tends to occur. Also, the temperature of the battery surface becomes high. Therefore, if discharging is performed before that, the temperature of the battery surface decreases, and gas generation stops. The amount of electricity charged at the start of discharging is preferably 90% or less of the theoretical amount of electricity of the positive electrode, more preferably 80% or less.

According to a third aspect of the present invention, in the method of the first or second aspect, the amount of electricity of the repeated discharge and charge in the repetitive process is made substantially equal, and the amount of electricity is 2% of the theoretical amount of electricity of the positive electrode. As described above, the number of repetitions is three or more.

Charging is performed to compensate for the amount of discharged electricity. If the amount of charged electricity is greater than the amount of discharged electricity, overflow and swelling of the battery case are likely to occur due to gas generation and an increase in battery temperature. Charge the same amount of electricity as the amount of electricity discharged.

The formation efficiency is increased by repeating the discharging and charging, and it is more effective if the number of times is three or more. However, the formation efficiency is not further increased even if the number is repeated six or more times. The deeper the depth of discharge, the higher the formation efficiency. The discharge is preferably at least 2% or more of the positive electrode theoretical electric charge, more preferably 4% or more, and still more preferably 8% or more. In the process of repeated discharging and charging, if the current is small, the formation time will be long,
It is preferable to perform discharge and charge with a relatively large current that can discharge or charge a predetermined amount of electricity in about 15 minutes to 1 hour.

The fourth invention of the present application is the method according to the first, second or third invention, wherein the total amount of charge obtained by subtracting the total amount of discharge from the total amount of charge is 100% of the theoretical amount of positive electrode. As described above, it is characterized by being 190% or less. If the total charge electricity obtained by subtracting the total discharge electricity quantity from the total charge electricity quantity is 100% or more of the positive electrode theoretical electricity quantity, the formation can be achieved by combining with the addition of 20% lead tin to the unformed cathode plate. A positive electrode plate having 90% or more of PbO ₂ can be obtained later, but more preferably 120% or more. However, when the thickness of the positive electrode plate is increased, 120% is not sufficient, and it is preferable to charge a larger amount of electricity. Further, by further increasing the amount of charged electricity, it is possible to increase the utilization rate of the positive electrode active material particularly at the time of high-rate discharge, and it is preferably 150% or more of the theoretical amount of electricity of the positive electrode. It is difficult to improve the utilization rate above.

The total quantity of electricity is 10 times the theoretical quantity of electricity of the positive electrode.
Being able to form at 0% means reducing the amount of electricity by up to about 70% compared to the conventional amount of electricity, by about 20%
The effect is very large as compared with the conventional method in which only the amount of electricity can be reduced. Note that the total charge amount is obtained by subtracting the total discharge amount from the total charge amount, but by regenerating the discharge amount, the energy can be effectively used.

The fifth invention of the present application is the method according to the first, second, third or fourth invention, wherein a dilute sulfuric acid having a predetermined specific gravity and a liquid amount taking into account the amount of liquid reduction during chemical formation is prepared before starting chemical formation. It is characterized in that the liquid is injected and the liquid amount or specific gravity is not adjusted during or after the formation.

By repeating the steps of discharging and charging in the course of the formation to suppress the total amount of overcharge, the amount of liquid reduction due to overcharge can be suppressed, and by appropriately changing the charging current, Since the overflow can be prevented, the formation can be performed without the need for adjusting the liquid amount or specific gravity of liquid replacement, re-injection, and the like, thereby reducing costs by reducing the number of steps.

According to a sixth aspect of the present invention, in the method according to the first, second, third, fourth or fifth aspect, the lead storage battery is a control valve type lead storage battery, a safety valve is mounted, and a temporary lid or an upper lid is provided. Is formed after fixing.

When these chemical conversion methods are applied to a control valve type lead-acid battery in which the electrolytic solution after chemical formation is restricted, it is possible to increase the efficiency of hermetic reaction during chemical formation by installing a safety valve and fixing a temporary lid. Gas generation can be suppressed. Further, even if the battery is left after the formation, it is shut off from the outside air by the safety valve, so that deterioration of the negative electrode plate and self-discharge can be prevented. Furthermore, by fixing not the temporary lid but the upper lid that should be used, the step of replacing the temporary lid with the upper lid after the formation can be omitted, and the cost can be further reduced.

According to a seventh aspect of the present invention, in the method according to the first, second, third, fourth, fifth or sixth aspect, the chemical conversion is performed in a gas phase.

By performing these chemical conversion methods, it is possible to prevent the battery temperature from increasing during the chemical formation, to perform the chemical formation without the need for a special cooling device such as a water tank facility, and to further effectively use the space. Because it can be used, significant cost reduction is possible.

[0026]

1 and 2 are diagrams showing an example of a current pattern at the time of chemical formation when the battery case forming method of the present invention is used. In FIG. 1, charging and discharging are repeated six times, and the charging current changes in three stages before and after this repetition process. The current after the repetition process changes in two stages, because the current was reduced immediately after the above process to prevent overflow, and then increased to shorten the formation time. In FIG. 2, charging and discharging are repeated three times, and the charging current changes in two stages before and after the repetition process. Note that the amount of charged electricity and the amount of discharged electricity are almost the same in each case. Thus, the battery case formation method of the present invention is carried out using, for example, the above-described current pattern.

Next, the present invention will be further described with reference to a specific example in which the present invention is applied to a control valve type lead storage battery.

(Example 1) First, dilute sulfuric acid having a predetermined specific gravity and a liquid amount in consideration of the amount of liquid reduction during chemical formation is injected into a lead-acid battery assembled with unformed positive and negative electrode plates, and then a safety valve is attached. . Thereafter, a temporary lid is attached and fixed to prevent the safety valve from coming off due to gas generation during chemical formation. The current at the start of formation and the amount of charge before discharge were set to the same conditions, and the depth of discharge, the number of charge / discharge repetitions, and the total amount of charge were varied. In addition, to the positive electrode plate used in this battery, 20% of lead was added to improve the formation efficiency. The ratio of PbO ₂ in the positive electrode active material of the lead storage battery thus obtained was analyzed. The results are shown in Table 1 below. The amount of electricity before discharge, the depth of discharge, and the total amount of charge are the ratios to the theoretical amount of electricity of the positive electrode.

[0029]

[Table 1]

As shown in Table 1, the deeper the depth of discharge, the higher the ratio of PbO ₂ . As for the number of repetitions, the ratio of PbO ₂ is higher when the number of repetitions is six than when the number of repetitions is three. In addition, even if the total amount of charged electricity is 100% of the theoretical amount of electricity of the positive electrode, 90% or more of PbO ₂
Is obtained, but at 120% of the theoretical quantity of electricity of the positive electrode, 96
%.

(Example 2) As in Example 1, first, dilute sulfuric acid having a predetermined specific gravity and a liquid amount in consideration of a liquid reduction amount during chemical formation is injected into a lead-acid battery assembled with unformed positive and negative electrode plates. After that, attach the safety valve and fix the temporary lid. The current at the start of the first charge, the amount of charge before discharge, the depth of discharge, and the number of repetitions of charge / discharge were set under the same conditions, and the total amount of charge was varied. In addition, to the positive electrode plate used in this battery, 20% of lead was added to improve the formation efficiency. When the rated capacity is expressed as C using the lead storage battery thus formed, 4 CA
Discharge was carried out at a current of. Table 2 below shows the ratio between the amount of discharge electricity and the theoretical amount of cathode electricity, that is, the utilization rate of the cathode active material. The total amount of charged electricity is a ratio to the theoretical amount of electricity of the positive electrode.

[0032]

[Table 2]

As shown in Table 2, the higher the total charge, the higher the utilization rate of the positive electrode active material. However, when the total charge is 190% of the theoretical positive charge, the reverse occurs. The utilization rate of the positive electrode active material is lower than at the time of 170%.

Example 3 Similarly to Examples 1 and 2, first, dilute sulfuric acid having a specific gravity and a liquid amount in consideration of a reduced amount during formation was added to a lead-acid battery assembled with unformed positive and negative electrode plates. After the injection, attach a safety valve and fix the temporary lid. The current at the start of the initial charge and the amount of charge before discharging were changed, and the depth of discharge, the number of charge / discharge repetitions, and the total amount of charge were the same. In addition, to the positive electrode plate used in this battery, 20% of lead was added to improve the formation efficiency. Using the lead-acid battery thus obtained, the rated capacity is changed to C as in the second embodiment.
The discharge was carried out at a current of 4 CA when Table 3 below shows the ratio between the amount of discharge electricity and the theoretical amount of cathode electricity, that is, the utilization rate of the cathode active material. The quantity of electricity charged before discharging is a ratio to the theoretical quantity of electricity of the positive electrode.

[0035]

[Table 3]

As shown in Table 3, the utilization rate of the positive electrode active material was higher when the charged amount of electricity before discharging was 77% or 66% of the theoretical amount of electricity of the cathode than 90% of the theoretical amount of cathode. Has become.

[0037]

According to the present invention, there is no need for a water tank facility or an overflow preventing jig, etc.
It is not necessary to adjust the amount or specific gravity of the liquid during the formation or re-injection after the formation, and furthermore, it is possible to realize a method for forming a battery case of a lead storage battery which has a high formation efficiency and can reduce the formation cost. .

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a current pattern during formation when the present invention is used.

FIG. 2 is a diagram showing another example of a current pattern during formation when the present invention is used.

FIG. 3 is a diagram showing a conventional current pattern during formation.

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Claims (7)

[Claims] 1. A chemical conversion method for forming an unformed electrode plate in a battery case, comprising a step of repeating discharge and charge during the formation, wherein the charging current changes by two or more steps before and after the step. A method for forming a battery case of a lead storage battery, comprising: 2. The amount of electricity charged is 100% of the theoretical amount of electricity of the positive electrode.
2. The battery case formation method for a lead-acid storage battery according to claim 1, wherein the discharge in the process of repeating the discharging and charging during the formation is started before the temperature exceeds. 3. The amount of electricity of repetitive discharge and charge in the repetitive process is substantially equal, the amount of electricity is 2% or more of the theoretical amount of electricity of the positive electrode, and the number of repetitions is 3 or more. The method for forming a lead-acid battery according to claim 1 or 2. 4. The total charge electricity amount obtained by subtracting the total discharge electricity amount from the total charge electricity amount is 100% of the positive electrode theoretical electricity amount.
At least 190% or less.
4. The method for forming a battery case of a lead storage battery according to 2 or 3. 5. Dilute sulfuric acid having a predetermined specific gravity and a liquid amount in consideration of the liquid reduction amount during chemical formation is injected before the start of chemical formation, and the liquid amount or specific gravity is not adjusted during or after chemical formation. The method for forming a battery case of a lead-acid battery according to claim 1, 2, 3, or 4. 6. The lead according to claim 1, wherein the lead storage battery is a control valve type lead storage battery, the safety valve is mounted, and the temporary lid or the upper lid is fixed, and then the formation is performed. A battery case formation method for storage batteries. 7. The method according to claim 1, wherein the formation is carried out in a gas phase.